Abstract
Our previous studies showed that 17β-estradiol (E2) modulated dopamine D2 receptor in regulating body weight set-point. The aim of this study was to understand whether thiamine deficiency influenced the E2 modulation on dopamine D2 receptors, using bromocriptine mesylate (BR) and sulpiride (SUL) as selective central dopamine-D2 receptors agonist and antagonist respectively. We studied the E2-dopamine D2 receptors interferences in a 10-day thiamine-deficient female rats for which consumptions of water, sugar, alcohol and food were daily-recorded and their consequences on body weights assessed. Our results showed that the volume of water daily ingested doubled in thiamine-deficient female rats (OXT), while sugar and alcohol consumptions collapsed with decreased weight and food consumption. On the one hand, thiamine potentiated D2/BR activity (bromocriptine-activated D2 receptors) to induce sugar intake and inhibited the same D2/BR receptors to induce water intake. On the other hand, thiamine promoted D2/SUL receptors (sulpiride-inhibited D2 receptors) for enhanced alcohol intake, increased food consumption and weight gain. Taking together, thiamine modulated the actions of 17β-estradiol on both D2/BR and D2/SUL receptors activities.
Highlights
IntroductionThiamine is involved in the process of glycolysis through the acid cycle for ATP production and cellular energy supply [2] [3]
The last observations suggest that under physiological conditions, the tonic inhibition of thiamine on water intake must be transmitted by the bromocriptine mesylate (BR)-activated dopamine D2 receptors (D2/BR)
We evaluated the effects of thiamine (B1 vitamin) deficiency on both 17β-estradiol (E2) and dopamine D2 receptors activities
Summary
Thiamine is involved in the process of glycolysis through the acid cycle for ATP production and cellular energy supply [2] [3]. Those metabolic aspects show up the coenzymatic function of the vitamin [4]. Thiamine deficiency decreased tyrosine hydroxylase in the brain [10]. These observations suggest that thiamine influences dopamine synthesis through its interactions with both L-tyrosine and tyrosine hydroxylase. Trovero et al [12] reported a modulatory effect of sulbutiamine, a synthetic thiamine, on dopaminergic cortical transmissions Together, these observations showed multiple facets of dopamine-thiamine interactions
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